Respiratory assistance device

ABSTRACT

The invention relates to a respiratory assistance device. According to the invention, communication means ( 34 - 39; 40 - 45 ) are provided between the distal opening ( 17 ) of the auxiliary channel ( 8 ) and the distal end ( 7 ) of the main channel ( 5 ). The aforementioned communication means can be opened and closed and, when open, said means form a passage that connects the main channel ( 5 ) with the exterior environment.

[0001] The subject of the invention is a respiratory assistance devicewhich can be used on patients whose spontaneous respiration is absent orinsufficient, whether or not they are placed under artificialrespiration.

[0002] Various devices are known, such as masks, oral, nasal,endotracheal or tracheotomic catheters or cannulae, designed to form thejunction between an artificial and/or anaesthetic respiration apparatusand the respiratory system of a patient. These devices, essentially inthe form of tubes, may, according to need, comprise immobilizing means,such as lugs or flanges close to the proximal end, for holding them overthe patient's mouth or nose, or else inflatable cuffs close to thedistal end, for holding them by friction in the trachea.

[0003] Known devices have significant drawbacks. Thus, for example, whena tube of known type is disconnected from the artificial respirator andthe patient needs oxygen-enriched air it is necessary to insert acatheter connected to an oxygen source into said tube. Moreover, in thecase of insufficient spontaneous respiration, the patient mustnecessarily remain connected to the respirator until the completereestablishment of his spontaneous respiration.

[0004] Therefore, in order to overcome these drawbacks, respiratoryassistance devices have already been proposed, for example in documentsEP-A-0 390 684, EP-A-0 701 834 and EP-A-0 978 291, which devices, apartfrom the main channel formed by the tube, comprise at least oneauxiliary channel, for example made in the wall of said tube, allowing astream of breathable gas to be injected for the patient's ventilation,this auxiliary channel emerging in the main channel in front of thedistal end thereof.

[0005] In these devices, the breathable gas feeding the auxiliarychannel is usually pure oxygen. However, some patients, whose body isused to a high level of blood carbon dioxide, are not able to withstandventilation with pure oxygen, which would lead to a risk of a mild heartattack.

[0006] The object of the present invention is to improve the respiratoryassistance devices summarized above in order to allow them to take thesituation of these latter patients into account.

[0007] To this end, according to the invention, the respiratoryassistance device comprising a tube which forms a main channel and whichis designed to be connected by its distal portion to a respiratoryairway of a patient such that said main channel connects the respiratorysystem of said patient to the outside, said device further comprising atleast one auxiliary channel connected to a source of breathable gas inorder to be able to blow a stream of such a breathable gas into saidrespiratory system and emerging in said main channel by at least onedistal orifice arranged in front of the distal end of the latter, isnoteworthy in that it comprises, between said orifice of said auxiliarychannel and said distal end of said main channel, communication meanswhich can be opened and closed and, when open, are capable of forming apassage connecting said main channel to the external environment.

[0008] Thus, by virtue of the present invention, when said communicationmeans are open, external air is sucked through them via said breathablegas stream, the air thus introduced diluting said breathable gas thatcan then be tolerated by the patient whose situation has been summarizedabove.

[0009] Preferably, so that the device can be adapted to allcircumstances and to all patients, it is advantageous that said passageconnecting said main channel to the environment has a variable crosssection. Thus, it is possible to adjust the dilution of the breathablegas by the ambient air in an optimum manner.

[0010] In one practical embodiment of said communication means, thelatter are of the type with a sideways-drilled rotary ring capable ofuncovering passages of different diameters. Such a ring may be mounteddirectly on said tube or else on a funnel in communication with saidmain channel.

[0011] It is advantageous that, facing the distal orifice of saidauxiliary channel, means for deflecting said ventilating breathable gasstream toward the axis of said channel be provided and that saidcommunication means be placed between said deflecting means and saiddistal end of the main channel. This is because, in this case, saiddeflecting means create, in said main channel, a vacuum that enhancessuction of the ambient air through said communication means.

[0012] The figures of the appended drawing will make it easier tounderstand how the invention can be produced. In those figures,identical references denote similar elements.

[0013]FIG. 1 is a schematic and partial view, in enlarged axial section,of one embodiment of a device of the invention.

[0014]FIGS. 2, 3, and 4 are cross sections along the lines II-II,III-III, and IV-IV, respectively, of FIG. 1.

[0015]FIG. 5 shows, in a view similar to FIG. 1, a variant embodiment ofthe device according to the invention.

[0016]FIG. 1 shows, schematically and on a large scale, only theproximal 2 and distal 3 portions of one embodiment 1 of the deviceaccording to the invention. This embodiment may constitute, for example,an oronasal endotracheal catheter with or without a cuff, a pediatricendotracheal catheter, a gas-monitoring catheter, an endobronchialcatheter, a nasopharyngeal catheter, an anatomical intubation catheterfor a child, a neonatal Cole catheter, a Gedel cannula catheter, anoxygen therapy nasal catheter, a nasal or bucconasal mask or a nasalballoon for treating sleep apnea.

[0017] The device 1 comprises a tube 4 which is flexible or preformed(in order to match the morphology of the patient), defining a mainchannel 5 having a proximal orifice 6 and a distal orifice 7 at the endsof said tube, respectively.

[0018] Thus, the main channel 5 is capable of providing the passagebetween the orifices 6 and 7, one (the orifice 7) of which is designedto be placed inside the respiratory airways of a patient, and the other(the orifice 6) of which is designed to be placed outside said patient.This orifice 6 may emerge outside and, in such a case, the patient mayinhale fresh air and exhale contaminated air through the main channel 5.It is also possible, as is explained hereinbelow, to connect the orifice6 to a source of pressurized breathable gas and to provide a system ofunidirectional valves, such that the patient inhales the breathable gasfrom said source through said main channel 5 and exhales thecontaminated gas to the outside, also through this main channel.

[0019] The diameter of the main channel 5 is of the order of a fewmillimeters. Satisfactory tests were carried out with diameters of 3 mm,7 mm, 8 mm, and 12 mm.

[0020] Moreover, auxiliary channels 8 are made within the thickness ofthe wall of the tube 4, the channels extending over practically theentire length of the main channel and being designed to be connected toa source of pressurized breathable gas, as is described hereinbelow.

[0021] The source of pressurized breathable gas may be connected bymeans of a ring 9, surrounding the tube 4 in a sealed manner, on thesame side as the proximal end 2, and defining a sealed annular chamber10 around said tube. The auxiliary channels 8 are placed incommunication with the chamber 10, using local cutaways 11 in the wallof the tube 4, and said chamber 10 is connected to said source ofbreathable air via a pipe 12. Of course, the proximal ends of thechannels 8 are closed off, for example by stoppers 13 inserted from theproximal end face 18 of the tube 4.

[0022] The auxiliary channels 8 have a smaller diameter than that of themain channel 5. The diameter of the auxiliary channels 8 is preferablyless than 1 mm and, advantageously, it is about 400 to 800 microns. Onthe distal side, the auxiliary channels 8 emerge in a recess 14 of theinner wall 15 of the tube 4. The recess 14 is annular and centered onthe axis 16 of said tube. It comprises a face 14 a which issubstantially transverse or slightly inclined so as to form a flare inthe main channel 5 into which said auxiliary channels 8 emerge via theirorifices 17, and a face 14 b following on from the face 14 a andconverging in the direction of the axis 16.

[0023] Preferably, between the convergent inclined face 14 b and thedistal orifice 7, the inner wall 15 has a part 15A which is slightlyflared outward, as is illustrated by the angle A in FIG. 1.

[0024] Thus, when the auxiliary channels 8 are fed with pressurizedbreathable gas through the elements 9 through 12, the corresponding gasstreams come up against the inclined face 14 b, which deflects them inthe direction of the axis 16 (arrows F in FIG. 1), causing a region ofvacuum in the vicinity of the latter, enhancing the gas flow inside themain channel 5, from the proximal orifice toward the distal orifice.

[0025] Thus the patient's inspiration is enhanced.

[0026] Preferably, the distance between each of the orifices 17 and theorifice 7 is about 1 to 2 cm.

[0027] At least one additional channel 20 is provided within thethickness of the tube 4 so as to emerge at 20A in the vicinity of thedistal end 19 of the tube 4 and to act as a pressure take-off.

[0028] As a safety measure, a calibrated exhaust valve 21 may beprovided in the proximal end 2 of the tube 4. Thus, in the event ofaccidental overpressure in the main channel 5, a leakage of gas occursoutside the patient, through the wall of the tube 4, in order toeliminate this overpressure instantaneously.

[0029] As shown in FIGS. 2 and 3, the auxiliary channels 8 are arrangedregularly around the axis of the tube 4. They vary in number dependingon use (adult or child), but there are generally between 3 and 9.Furthermore, at least one of the auxiliary channels 8 may be speciallyadapted to provide a medical fluid.

[0030] The tube 4 of the device according to the invention may be madefrom any material already used in respiratory catheters, for example, apolyvinyl chloride, with an optional silicone coating, or from steel toallow high-pressure injections.

[0031] Of course, the dimensions of the device according to theinvention may be very variable, essentially depending on the airway inwhich the tube is placed and on the size of the patient, who may be anadult, a child, or a new-born or premature baby.

[0032] The device 1 further comprises a feed and control device 22 thatis respectively connected to the orifice 6 of the proximal end 2 of thetube 4 by means of a link 23 and to the additional channel 20 by meansof a link 24.

[0033] The feed and control device 22 is fed with pressurized breathablegas, for example pure oxygen, by a source 25, to which it is connectedby a pipe 26 on which an adjustable flow meter-pressure regulator 27 ismounted.

[0034] The outlet from the flow meter-pressure regulator 27 is connectedto the pipe 12 via a branch pipe 28 on which a controlable valve 29, anadjustable pressure-drop device 30 limiting flow rate and pressure (forexample a tube with a calibrated pipe), a humidifier 31 and a calibratedexhaust valve 32, with adjustable calibration, are mounted in series.The controlable valve 29 is controlled by the feed and control device 22via a link 33.

[0035] By way of nonlimiting example, the flow meter-pressure regulator27 may deliver, into the pipe 28, the breathable gas coming from thesource 25 at a pressure P, for example equal to 3.5 bar with a maximumadjustable flow rate of, for example, 32 liters per minute, while theflow rate and pressure limiter 30, receiving this breathable gas fromthe pipe 28, may reduce the pressure thereof down to a value p, forexample equal to 0.5 bar (for an adult) and to 0.07 bar (for a child),and the flow rate down to a value d, for example equal to 0.5 liters perminute. As for the exhaust valve 32, this is calibrated to the pressurep.

[0036] Moreover (see FIGS. 1 and 4), between the annular recess 14 andthe distal orifice 7, the wall of the tube 4 is drilled by through-holes34 to 37 that have different diameters and have distributed around theaxis 16. The holes 34 to 37 are covered by a ring 38, capable ofrotating with gentle friction around said tube 4 and itself providedwith a hole 39 which can be placed opposite one or other of the holes 34to 37 by rotating the ring 38. The hole 39 has a diameter at least equalto that of the hole 34, which is the largest of the holes 34 to 37. Thering 38 is trapped on the tube 4, by means of annular side ribs 40 and41.

[0037] As can be seen in FIG. 4, the ring 38 may take either at leastone position in which it closes off all the holes 34 to 37, or positionsin which the hole 39 is aligned with each of the holes 34 to 37,respectively. In these latter cases, on each occasion, a passage isestablished between the main channel 5 and the external environment,through the corresponding hole 34 to 37. Of course, the cross section ofsuch a passage is then determined by the cross section of the hole 34 to37 in question.

[0038] The operating modes of the device 1 according to the inventionare as follows:

[0039] in the artificial respiration mode, the ring 38 closes off allthe holes 34 to 37 and the feed and control device 22, on the one hand,closes the valve 29 via the link 33, such that the pipe 12 is not fedwith gas and, on the other hand, directs the breathable gas into thetube 4 via the link 23. This device 22 comprises means (not shown) foradjusting the pressure and the flow rate of the breathable gas that itreceives from the pipe 26 and that it directs to the tube 4. If anoverpressure occurs in the respiratory airway of the patient, it isdetected and transmitted, via the additional channel 20 and the link 24,to the device 22, which stops its operation. Furthermore, if thisoverpressure exceeds the calibration threshold of the calibrated valve21, for example if the additional channel 20 is obstructed by mucus andis not able to transmit the overpressure information to the device 22,this valve 21 opens and the proximal channel 5 is opened to theatmosphere;

[0040] in the respiratory assistance mode, the feed and control device22 cuts the link 23 in order to place the orifice 6 in communicationwith the atmosphere and controls the valve 29 via the link 33 so thatthe latter directs a continuous or pulsed stream of breathable gas tothe patient through the limiter 30, the humidifier 31, the calibratedexhaust valve 32, and the auxiliary channels 8. Moreover, the ring 38 isrotated in order to bring the hole 39 opposite one of the holes 34through 37, such that communication is made between the main channel 5and the external environment, downstream of the annular recess 14, wherea region of vacuum is generated by the gas streams coming out of theauxiliary channels 8. Next, external air is sucked through saidcommunication (see arrow f) and mixed with said gas streams, and is thusdiluted. Of course, the dilution rate of these gas streams depends onwhich hole 34 through 37 they pass through. It may be noted that, forconstant injection conditions of said streams, the dilution ratecorresponding to each of the holes 34 through 37 may be calibrated onceand for all, such that it is possible to deliver to a patient thebreathable air-gas mixture most suitable to his case by choosing thehole 34 through 37 opposite which the hole 39 of the ring 38 will bebrought. If an overpressure occurs in the respiratory airway of thepatient, as was described above, this overpressure is detected andtransmitted by the additional channel 20, such that the device 22 closesthe valve 29 and such that the pipe 28 stops directing gas to thepatient. If the additional channel 20 is obstructed, the device 22 isnot alerted to the overpressure in the respiratory airway of the patientand is unable to stop, but this overpressure leads to an increase inpressure in the auxiliary channels 8 and the pipe 12. When this pressureincrease reaches the opening threshold of the safety valve 32, thelatter opens and the breathable gas stream is no longer directed to thepatient, but on the contrary is diverted to the outside by said safetyvalve 32. Thus, although in the latter case the safety system 20A, 20,24, 22, 29 might be unable to operate, the breathable gas stream cannotreach the respiratory system of the patient.

[0041] In the variant embodiment 1.1 of FIG. 5, operation is identicalto that described above. In this variant embodiment, a blind funnel 40is provided, in communication via a channel 41 with the main channel 5,said funnel being provided with a side hole 42 covered by a rotary ring48. This latter ring is drilled with holes 44, 45 with differentdiameters, the largest equal to that of the hole 42, and it is able, byrotation, either to close off the hole 42, or to bring one of the holes44, 45 opposite the hole 42.

[0042] Thus, from the foregoing, it can be seen that it is possible todilute with air, in any desired proportion, the gas streams coming fromthe source 25 and passing through the auxiliary channels 8.

1. A respiratory assistance device comprising a tube (4) which forms amain channel (5) and which is designed to be connected by its distalportion (3) to a respiratory airway of a patient such that said mainchannel (5) connects the respiratory system of said patient to theoutside, said device further comprising at least one auxiliary channel(8) connected to a source (25) of breathable gas in order to be able toblow a stream of such a breathable gas into said respiratory system andemerging in said main channel (5) by at least one distal orifice (17)arranged in front of the distal end (7) of the latter, means (14 b) ofdeflecting said ventilating breathable gas stream toward the axis (16)of said main channel (5) being provided facing said distal orifice (17)of said auxiliary channel (8), characterized in that it comprises,between said deflecting means (14 b) and said distal end (7) of saidmain channel (5), communication means (34-39; 40-45) which can be openedand closed and, when open, are capable of forming a passage connectingsaid main channel (5) to the external environment.
 2. The device asclaimed in claim 1, characterized in that the passage connecting saidmain channel to the environment has a variable cross section.
 3. Thedevice as claimed in claim 2, characterized in that said communicationmeans are of the type with a sideways-drilled rotary ring (38, 43)capable of uncovering passages of different diameters.
 4. The device asclaimed in claim 3, characterized in that said rotary ring (38) ismounted directly on said tube (4).
 5. The device as claimed in claim 3,characterized in that said rotary ring (43) is mounted on a funnel incommunication with said main channel (5).